Photographic emulsion



atented Aug. 7,15

' e i r snow I Burt H. Carroll and .iohn Spence, ch, N. Y,

it to Eastman Kodak @ompany, t

a at z e, N. Y., a, corporation of New J y No Drawing. Application .ian r r 314,. M43,

Serial No. 472,340

12 Claims. (Ci. 395-7) This invention relates to sensitized photo- The majority oi cyanine dyes which are supergraphic emulsions and more. particularly to specsensitized by the aromatic nitriles are charactertraily (optically) sensitized 4 emulsions. ized by the iactthat the dyes produce two types It is known that the distribution of spectral of sensitization depending upon conditions. Such sensitivity 01' certain spectrally sensitized emul- 5 difl'erent types of sensitization are described by alone can be altered and an increase of sensitivity Leermakers, Carroll and Stand, J. Chem. Physics, obtained in some spectral region by incorporat- ,5, 878 (i937) and by G. Schwarz, Sci. et Ind.

certain additional sehsitiflnc dyes in the spec- Phot. 10, 233 (1939;). When certain cyanine dyes trcliy sensitized emulsions. (See United States of this type are used as sensitizers in low con- Patents 2,158,882, dated May 18, 1939, and 2,159,- centrations, they exhibit a sensitizing mourn 667, dated May 23, 1939.) The eflect thus 01 displaced about 20. to 50 mu toward the red from tained has come to be known as supersensitizathe absorption maximum in ethyl alcohol solution. Supersensitization of certain speetrally 'tion. .On increasing the concentration of the. sensitized emulsions can alsobe effected by indye, or upon digesting the emulsion containing corporating certain substantially colorless heterothe dye in the lower concentration, or both, a cyclic bases in the spectrally sensitized emulsecond maximum of sensitization develops at sions. (See United States Patent 2,177,635, dated longer wavelengths, which may be accompanied October 31, 1939.) Supersensitization difl'ers by an increase in total optical sensitization. In from hyperscnsitization which involves treatment some cases a decrease in sensitivity at the first of finishedfilms or p1ates, an operation which maximum can be detected. These phenomena normally reduces thepAg and increases the pH are consistent with the hypothesis of two states oi the emulsions with consequent decrease in staof the sensitizing dye in an equiiibri which is bimycontrolled by concentration. The aromatic We have now found a new method for supernitriles favor the formation oi a second maxi- Sensltizing Sp ysensitized e u s w ich mum. The increase in sensitivity apparently cornot only does not reduce the stability of the emulresponds to increased conversion of the dye to 8110115. but is p ally valuable as a means of the state corresponding to the second maximum giving panchromatic sensitized emulsions of high of sensitization. In some cases the eflect appears speed and 800d color balance. to correspond to a more complete conversion than It is, accordin y, an obiectof our invention to has ever been previously obtained without a suill'ovide n Supersensitized P t p emulpersensitizer and in any case the long wavelength sions. A further object is to provide aproce'ss sensitivity is better than can be obtained irom for preparing ch emulsions- Still h r o j t the same concentration of dye without the arowill become apparent'hereinafter. matic nitrile.

- In accordance with the invention, a photo- The following are exemplary oi the ce aphic silver halide emulsion 'sp fl n dyes which can be supersensitized in accordance tized with a' cyanine dye is supersensitized by th ur invention:

incorporating in the emulsion certain aromatic 1,l-d1ethyl-6,6 -dimethyl-2,2 -cyanine iodide nitriles, viz. one or more of those represented by 1,'3 diethy1se1ena 2, cya' i e i in de the following general formula: 3,3-diethyl-Q-methylthiacarbocyanine bromide r- 3,s'- diethyl c methylselenacarbocyanine browherein D represents an aromatic nucleus devoid midi! of nitro groups and acidicsroups', e. g. sulionid hyl-3,3'-dimethyle,5.4',5'-dlbenzothiacarb0- acid groups (and their salt forms) and sulflnic cyanim bromide acid groups (and their salt forms). The nitriles The sensitizing dyes can be employed in any in whim D represents an ammtic nucleus of the desired concentration. Ordinarily from 10 to so benzene series areadvantageously employee mg. of dye per liter of emulsion will sufice to proemplary of the aromatic nitriles are the followduce the optimum ensitizing sheets. The methmg: i ads of incorporating sensitizing dyes in emulsions Benzonitriie is won known to those skilled in the art. omip-Chlorobenzonitrile narily, it is preferable to dissolve the dye m a. p-Bromobenzonitrile water-miscible solvent, such as methanol, before p-Methoxybenzonitrile incorporating in the emulsion. 2,5-dimethoxybenz nitrile The amount of the aromatic nitrile used is not 'y-Phenoxybuty ronitrile critical. Usually the .full supersensitizlng eil'ect p t is developed at a concentration 0! from 0.2 to 2 'fi-Nflph h n t e grams per liter of emulsion, but larger or smaller Hydroquinone di-p cyanoethyl ether amounts are sometimes advantageous. The aro- 2,3-dicyanohydroquinone dimethyl ether matic nitriles can be added with, before, 0 after the sensitizing dye or dyes. The aromatic nitriles are preferably, but not necessarily, diluted with a water-miscible solvent, such as methanol, be-' fore incorporation in the emulsion. One or more aromatic nitriles can be employed.

The following examples will serve to illustrate results obtained in accordance with the invention: I

Example 1 Red Minus blue Aromatic nitri le F (gJliter oi emulsion) 1 g Speed Gamma Speed Gamma None l30 l. 30 725 1. 34 05 Benzonitrile, 1.25.. 178 1. 36 615 1. 48 05 p-Bromobenzo-nitrile,

1.25 210 I 1. 32 690 l. 45 .05 2,5- dlmsthoxy-benzm nin'ils, 1.25 255 l. 35 605 l. 55 05 Erample 2 I Another fast negative geiatino-silver-bromi-' increase of sensitivity in some spectral region, cause a decrease in others, and must be employed with this fact in mind. In the above examples, the minus blue speed demonstrates whether or not there is a loss of total spectral sensitivity owing to a decrease of speed in some spectral region. Some of the aromatic nitriles while eii'ecting supersensitization and changingthe distribution oi spectral sensitivity, cause overall desensitization of. the emulsion. Examples of such aromatic nitriles are following: p-methoxy-benzonitrile, a-naphthonitrile and p naphthonitrile.

Our invention is primarily directed to the cus tomarily employed gelatino-silver-halide developing-out emulsions, such as gelatino-silver-chloride, gelatino-silver-chldrobromide, gelatino-silyer-bromide and gelatino-silver-bromiodide developing-out emulsions.

Emulsions prepared in accordance with our invention can be coated in-the usual manner upon any desired support, such as cellulose nitrate support, cellulose acetate support, polyvinyl acetal resin support, metal support, glass support or paper support.

What we claim as our invention and desire to be secured by Letters Patent oi the United States is: Y

A photographic silver halide emulsion spectrally sensitized with a cyanine dye. containing, as

odide developmg-out emulsion was sensitized with 3,3 diethyl ii-methyl-selenacarbocyanine bromide (20 mg. per liter of emulsion) and to the spectrally sensitized emulsion was added Yr phenonybutyronitrile. A portion of'the spectrally sensitized emulsion was exposed without, and another portion with the addition of the aromatic nitrilethrough red (Wratten 25) and minus blue (Wratten 12) filters, the latter giving a good measure of total optical sensitization.

Ir 4 Rod Minus blue -phenoz butyronitrile Jliter of Fog emuhlon Speed Gamma Speed Gamma NDHG i- 89 1. 71 405 1. 54 1O 25 148 1.74 415 1.63 .07

Example 3 A fast negative gelatino-silver-bromiodide developing-out emulsion was sensitized with 9- methyl 3,3 diethyi -4,5,a',5'-d ibenzothiacerbocyanine bromide (15 mg. per liter of emulsion) and to the spectrally sensitized emulsion was added benzonitrile. A portion of the, spectrally sensitized emulsion was exposed without, and another portion with the addition of the nitrile, through 'red (Wratten 25) and minus blue (Wratten 12) filters, the latter giving a good measure of total Optical sensitization.

-Minus blue Benzonitrile (g. tor

of emulsion Fog Gamma Speed Gamma Some of the aromatic nitriles, while eflecting an emulsion spectrally sensitized with a cyanine dye.

a supersensitizer, an aromatic nitrile of the following general formula:

D-X wherein D representsan aromatic nucleus devoid of nitro groups and acidic groups and salt forms groups. v

2. Aphotographic silver halide developing-out containing, as 'a super-sensitizer, an aromatic nitrile' ofthe following general formula:

wherein D represents an aromatic nucleus devoid of nitro groups and acidic groups and salt forms groups.

of said acidic groups and x represents a member selected from the group consisting of sync groups; cyanoalkyl' groups and cvanoallrcl ir S uP 3. A photographic gelatino-silver-halide emulsion spectrally sensitized with a cyanine dye containing, as a super-sensitizer, an aromatic nitrile of the following general formula:

wherein D represents an aromatic nucleus .cyanine dye containing, as a supersensitizer, an

aromatic nitrile of the 19110171118 general formula:

wherein D represents an aromatic nucleus devoid of riitro' groups and acidic groups and's'alt forms of said acidic groups and X represents a member selected from the group consisting of cyano groups, cyanoalkyl groupsand cyanoalkoxy 5. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion atone concentration and at a higher concentration, or

upon digestion of the emulsion containing the,

dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, an aromatic nitrile of the. following general formula:

wherein D represents an aromatic nucleus devoid of nitro groups and acidic groups and salt forms of said acidic groups and X represents a member selected from the group consisting of cyano groups, cyanoalkyl groups and cyanoalkoxy groups. 4

6. A photographic gelatino-silver-halide developing-out emulsion spectrally senitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, an aromatic nitrile of the following general formula:

wherein D represents an aromatic nucleus of the benzene series devoid of nitro groups and acidic groups and saltform's of said acidic groups and X represents a member selected from the group consisting of cyano groups, cyanoalkyl groups and cyano-alkoxy groups.

7. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a'wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, an aromatic nitrile of the following general formula' DCN wherein D represents an aromatic nucleus of the benzene series devoid of nitro groups and acidic groups and salt forms of said acidic groups.

8. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, anaromatic nitrile of the following general formula:

wherein D represents an aromatic nucleus of the benzene series devoid of nitro groups and acidic groups and salt forms of said acidic groups and X represents a cyanoalkyl group.

9. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or

upon digestion of the emulsion containing the dye at the' lower centration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, an aromatic nitrile of the following general formula:

wherein D represents an aromatic nucleus of the benzene series devoid of nitro groups and acidic groups and salt forms of said acidic groups and X represents a cyanoalkoxy group.

10. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, benzonitrile.

11. A photographic gelatino silver-halide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, -y-phenoxybutyronitrile.

12. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized-with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion containing the dye at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum said emulsion containing, as a supersensitizer, phenylacetonitrile.

' BURT H. CARROLL.

JOHN SPENCE. 

